A dynamic packet relay method of a personal area network (PAN) coordinator in a sensor network includes receiving a Child_Register message that includes information about a device associated with a coordinator and building or updating a network hierarchical structure; monitoring reception of a packet or a beacon from the coordinator and determining whether the coordinator is defective or not; and in response to a determination that the coordinator is defective, changing the current coordinator to one of devices belonging to a PAN as a new coordinator.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A dynamic packet relay method of a personal area network (PAN) coordinator and a device associated with the PAN coordinator in a sensor network, the dynamic packet relay method comprising: receiving, at the PAN coordinator, a Child_Register message that includes information about a device associated with a coordinator and building or updating a network hierarchical structure; monitoring, at the PAN coordinator, reception of a packet or a beacon from the coordinator and determining whether the coordinator is defective or not; in response to a determination that the coordinator is defective, changing, at the PAN coordinator, a current coordinator to one of devices belonging to a PAN as a new coordinator wherein during an inactive period of the RAN coordinator, the device associated with the coordinator transmits a packet to the coordinator and receives a beacon from the coordinator, and wherein, when the coordinator is defective, one of the devices belonging to the PAN that received the packet transmitted during the inactive period of the PAN coordinator is determined as the new coordinator.
2. The dynamic packet relay method of claim 1 , wherein the information about a device includes a media access control (MAC) extended address, a MAC short address, and guaranteed time slot (GTS) information.
3. The dynamic packet relay method of claim 1 , wherein the network hierarchical structure includes the MAC extended address, the MAC short address and the GTS information, which are device information, and an associated MAC extended address and an associated MAC short address which are information about the coordinator associated with the device.
4. The dynamic packet relay method of claim 1 , wherein the determining of whether the coordinator is defective or not comprises: monitoring the reception of a packet or a beacon from the coordinator for a predetermined time period, in response to no beacon or data being received for the predetermined time period, sending an Alive Request message to the coordinator, and in response to no response to the Alive Request message being received from the coordinator, determining that the coordinator is defective.
5. The dynamic packet relay method of claim 1 , wherein the changing of the current coordinator comprises: broadcasting a Coordinator_Candidate Request message throughout the PAN, receiving a Coordinator_Candidate Response message from all devices belonging to the PAN, selecting one device with the best communication quality by analyzing the received Coordinator_Candidate Response messages, and sending a Coordinator Request message to the selected device.
6. The dynamic packet relay method of claim 5 , wherein both the Coordinator_Candidate Request message and the Coordinator Request message contain information about the coordinator and the information about the device associated with the coordinator.
7. The dynamic packet relay method of claim 5 , further comprising: receiving, at the device associated with the PAN coordinator, a Coordinator_Candidate Request message from a PAN coordinator, the Coordinator_Candidate Request message containing coordinator information and information about a device associated with a coordinator; sending, from the device associated with the PAN coordinator, a Coordinator_Candidate Response message to the PAN coordinator, wherein the Coordinator_Candidate Response message contains information regarding a packet which has been received during an inactive period, the packet being transmitted to the coordinator from the device associated with the coordinator; and in response to receiving a Coordinator Request message from the PAN coordinator, changing, at the device associated with the PAN coordinator, a mode to serve as a coordinator from a following frame.
8. The dynamic packet relay method of claim 7 , wherein the sending of the Coordinator_Candidate Response message comprises: comparing a source address in a MAC header of the packet received during the inactive period, with an address of the device associated with the coordinator, and comparing a destination address with an address of the coordinator, calculating both a number of packets with source and destination addresses that match the addresses of the device and the associated coordinator and a value of received signal strength indication (RSSI) during designated frame periods, and creating the Coordinator_Candidate Response message using the calculated values.
9. A dynamic packet relay apparatus of a (personal area network) PAN coordinator comprising: a relay hierarchy generator configured to receive a Child_Register message that contains information about a device associated with a coordinator, and build or update a network hierarchical structure; a coordinator checker configured to monitor reception of a beacon or data from the coordinator to determine whether the coordinator is defective or not; a coordinator changer configured to, in response to a determination that the coordinator is defective, change a current coordinator to one of devices belonging to a personal area network as a new coordinator wherein during an inactive period of the PAN coordinator, the device associated with the coordinator transmits a packet to the coordinator and receives a beacon from the coordinator, and wherein, when the coordinator is defective, one of the devices belonging to the PAN that received the packet transmitted during the inactive period of the PAN coordinator is determined as the new coordinator.
10. The dynamic packet relay apparatus of claim 9 , wherein the coordinator checker comprises: a reception monitor configured to monitor the reception of data or a beacon from the coordinator for a predetermined time period, an alive-request sender configured to send an Alive Request message to the coordinator, and a defect determiner configured to, in response to no response to the Alive Request message being received from the coordinator, determine that the coordinator is defective.
11. The dynamic packet relay apparatus of claim 9 , wherein the coordinator changer comprises: a candidate requester configured to broadcast a Coordinator_Candidate Request message throughout a PAN, a device selector configured to receive Coordinator_Candidate Response messages from devices in the PAN, and select one device that has the best communication quality, based on the analysis of the received Coordinator_Candidate Response messages, and a change requester configured to send a Coordinator Request message to the selected device.
12. The dynamic packet relay apparatus of claim 11 , wherein both the Coordinator_Candidate Request message and the Coordinator Request message contain information about the coordinator and the information about the device associated with the coordinator.
13. The dynamic packet relay apparatus of claim 11 , wherein the device in the PAN comprises: a candidate request receiver configured to receive a Coordinator_Candidate Request message that contains coordinator information and information about a device associated with a coordinator from the PAN coordinator; a candidate response sender configured to send a Coordinator_Candidate Response message to the PAN coordinator, wherein the Coordinator_Candidate Response message contains information regarding a packet which has been received during an inactive period, the packet being transmitted to the coordinator from a device associated with the coordinator; and a mode changer configured to, in response to receiving a Coordinator Request message from the PAN coordinator, change a mode of the device to serve as a coordinator from the following frame.
14. The dynamic packet relay apparatus of claim 13 , wherein the candidate response sender comprises: a consistency checker configured to compare a source address in a MAC header of the packet received during the inactive period with an address of the device associated with the coordinator, and compare a destination address with an address of the coordinator, a packet information calculator configured to calculate both a number of packets with source and destination addresses that match the addresses of said device and said coordinator and a value of RSSI, during designated frame periods, and a response generator configured to create a Coordinator_Candidate Response message using the calculated values.
15. The dynamic packet relay apparatus of claim 9 , wherein the coordinator comprises: a device registration component configured to send a Child_Register message that contains information about a device associated with the coordinator to a PAN coordinator; a relay packet receiver configured to transmit a beacon to the associated device and receive, in turn, a packet from the device during an inactive period of the PAN coordinator; and a relay packet transmitter configured to transmit the packet to the PAN coordinator during an active period of the PAN coordinator.
16. The dynamic packet relay apparatus of claim 15 , wherein the device registration component sends the Child_Register message to the PAN coordinator each time the information about the associated device is changed.
17. The dynamic packet relay apparatus of claim 15 , wherein the device associated with the coordinator comprises: a beacon checker configured to, in response to no beacon being received from the associated coordinator, stand by for a predetermined time period to receive a beacon, and in response to a beacon being received, determine whether the received beacon was sent from the coordinator or another device; and a coordinator updater configured to, in response to a determination that the beacon was sent from another device, updating coordinator information based on information about the device.
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March 16, 2016
October 29, 2019
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